Patent GB-569961-A (GB)
Title: Improvements in or relating to telegraph apparatus
IPC: H04L15/18
Filed: 1943-09-16
Abstract: 569,961. Telegraphy. CABLE & WIRELESS, Ltd., and WARBURTON, F. Sept. 16, 1943, No. 15223. [Classes 40 (iii) and 40 (v)] A telegraph transmitter, particularly for wireless transmission when it may be necessary to repeat words, is constructed to transmit normally each word twice from a perforated tape on which the word appears only once, discriminating means being provided to detect a space between words and to initiate the second transmission of the preceding word before the transmission of the next word. The repeat transmission may be cut out when a single transmission is sufficient. The invention is described as applied to a Morse code transmitter but is stated to be also applicable to a type-printing transmitter employing a fiveunit code. General arrangement of parts and operation of transmitting contacts. A shaft 18, continuously rotating during transmission, carries four eccentrics 20 ... 23, of which eccentrics 22, 23 control the driving of two tape-feeding sprockets 3, 4, eccentric 20 actuates a rocker 30 about an axis to control the actuation of two pairs of tape peckers 6, 7 ; 8, 9 and of the transmitting contacts 81, 83, and eccentric 21 rocks a frame 33 about axis 34 to control mechanism for the selection of the operative sprockets and peckers. Each sprocket shaft is provided with a pair of ratchets 38, 39 ; 60, 61 with staggered teeth engaged by pairs of pawls 40, 41 ; 50, 51, the pawls of each pair being operated. in opposite phase by eccentrics 22, 23 so that at each rotation of shaft 18 the tape is advanced in two steps by one or other or both sprockets through a total distance equal to the distance between two centre perforations 2. Dots are represented on the tape by perforations 84, 88, Fig. 8, directly opposite one another and produce a marking signal during one halfrotation of shaft 18 and a spacing signal during the other half. Dashes are represented by perforations 86, 90 staggered to the extent of one centre perforation 2 and produce a marking signal during three half-rotations of shaft 18 and a spacing signal during the next halfrotation. Letters in a word are separated by the distance of two centre perforations and words by the distance of four centre perforations. The pairs of peckers 6, 7 ; 8, 9 are mounted on actuating members 100, 103 ; 101, 104 and selection of the pair to be operative is determined by a member 112 movable up or down by bell-crank lever 114 to lock one or other pair of actuating members. The peckers of the operative pair are slightly staggered and are alternately moved into engagement with the tape by pins 108, 111 on rocker 30. When a marking pecker 6 meets a perforation, an arm 133 depresses lever 141 to rock contact-controlling member 149. Member 149, through pin 160 engaging a cam surface, in turn rocks a contact-actuating member 162 causing leaf-spring 164 to close the marking contact 81. Member 162 is provided with an arcuate surface 58 centred on axis 150 to hold the member in its set position. Lever 146 is also rocked by a mark signal to raise levers 153, 154 and remains locked until a spacing signal is received. The operation when a spacing pecker 7 or 9 finds a perforation is similar, members 149, 162 being rocked in the opposite direction. At the same time, levers 146, 154 are released, but lever 153 remains held by latch 234, Fig. 2. Frame 33 rocked by eccentric 20 carries pawls A, B, C co-operating with ratchets AA, BB, CC. Double transmission of each word. When blank tape is passing, ratchets AA, CC are operated idly, their back-lock levers 187, 201 being out of engagement, and ratchet BB is not operated owing to pawl B being engaged by arm 191 of lever 153. When a mark perforation corresponding to the first letter of a word is reached, pawl B operates ratchet BB one step and a cam 223 on the ratchet causes backlock lever 187 to engage ratchet AA but pawl A is now inoperative owing to its engagement by arm 190 of lever 154. During the space between two letters, ratchet AA takes one step but when the first mark of the next letter is reached, pawl A actuates lever 230 to withdraw back-lock lever 187. The space between the pairs of peckers 6, 7 ; 8, 9 corresponds to four centre perforations and when the first letter perforation reaches sprocket 4, cam 223 on ratchet BB, which has advanced four steps, moves slide 238 to free rocking member 63. A lug 72 now engages an extension 70 of pawl 50 to render sprocket 4 inoperative. A loop in the tape is thus formed and a further pair of peckers 11 sensing the loop, move a bell-crank 219 controlling a catch 215. During the space between two words, ratchet AA advances three steps and a cam 254 actuates slides 242, 257. Slide 242 causes rocking member 63 to change over from sprocket 3 to sprocket 4 and slide 257 causes bell-crank lever 114 to change over from peckers 6, 7 to peckers 8, 9. The transmission of the word is now repeated and at the first mark, ratchet AA is released but catches 215, 265 respectively hold sprocket-discriminating member 63 and pecker-discriminating member 114. At the end of the second transmission, the tautening of the tape causes centre peckers 11 to rock bell-trank lever 219 causing sprocket 4 to stop and rendering back-lock lever 201 operative to hold ratchet CC. Ratchet CC moves four steps corresponding to the pause which must be inserted before the next work is transmitted and a cam 282 effects the release of ratchets AA, BB and lever 153. A further cam 293 acting on lever 203 renders both sprockets and the peckers 6, 7 operative again. Single transmission of each word. Rotation of spindle 315, Fig. 1, causes lever 319 to engage pawl B so that ratchet BB is not moved to initiate the operations resulting in the second transmission of a word.